An estimated 600,000 people so far have signed the Coalition For Marriage's campaign petition backing traditional marriage, a document supported by major United Kingdom religious figures like Lord Carey, the former Archbishop of Canterbury.

The Catholic Education Service said last month that it had contacted its 385 secondary schools in England and Wales asking them to circulate a letter by the Archbishops of Westminster and Southwark - the Most Reverend Vincent Nichols and the Most Reverend Peter Smith - that was recently read in parishes, defending the traditional definition of marriage.

The schools were also encouraged to consider publicizing the petition.

So-called humanist politicians accused Catholic schools of “political indoctrination” by promoting the campaign among schoolchildren. The government in Wales also is looking into whether the schools could be breaking equality and political impartiality laws.

But Leighton Andrews, the Welsh Assembly Government minister for education and skill, said that he had been advised by legal experts that the effort was not homophobic and therefore did not break equality laws.

He has ordered schools in Wales to give pupils a “balanced” view. They must also specifically tell pupils about the minister’s intervention.